Building Energy Savings Methods
How to cut building heating, cooling & other operating costs
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Building & mechanical system energy conservation:
These articles describe how to substantially reduce building energy usage and costs: building heating and cooling costs, electric bills, and heating fuel bills.
We describe how to make use of solar energy or wind energy, and we detail other energy saving steps for homes and commercial buildings: building air leak detection / sealing, optimum building insulation, energy efficient ventilation, home heat loss detection / remedy, heating system tuneup / adjustments, setting priorities on energy saving steps (get the most return on your energy-savings dollar), and selecting energy efficient windows and doors.
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Energy Conservation News Updates - Live
US Financial crisis increases building owner focus on do it yourself home repair & saving heating & cooling costs and interest in Do-It-Yourself Building Repairs found here.
Links at the "More Reading" links at the bottom of this article identify major energy-conservation or energy savings topics that we discuss. A list of key energy cost reducing articles is provided just below. Sketch at page top is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss, and discussed
at ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE.Sketch at left shows a solar water heating system, courtesy of Lennox Industries.
- AIR FILTERS for HVAC SYSTEMS and AIR FILTERS, OPTIMUM INDOOR
- AIR LEAK DETECTION TOOLS - how to find and fix air and heat leaks on buildings, an expert guide to weatherization. Air leaks in older homes overwhelm even high-R insulated walls and ceilings, increasing energy costs
- AIR LEAK SEALING PROCEDURE - step by step photo guide to stopping leaks around windows and doors
- AIR LEAK MINIMIZATION - how to retrofit a building to tighten a leaky house
- AIR POLLUTANTS, COMMON INDOOR - what indoor air contaminants are more likely in tight homes? what to do about them?
- AIR SEALING STRATEGIES - different strategies for sealing a leaky building to save energy
- APPLIANCE EFFICIENCY RATINGS - where to get energy efficiency ratings for air conditioners, clothes dryers, clothes washers, fans, refrigerators, stoves, water heaters, well pumps, etc.
- ROOF ICE DAM LEAKS - leaks into and out of building attics and roof cost energy and invite moisture/mold problems.
- BACKUP HEAT for HEAT PUMPS
- BASEMENT CEILING VAPOR BARRIER - where to put the vapor and air barrier in a basement ceiling, what to use
- BASEMENT HEAT LOSS - how to find and stop unwanted air and heat leaks from basements and crawl spaces
- BLOWER DOORS & AIR INFILTRATION - how we determine how leaky a building is or is not - measuring air changes per hour
- BUCKLED FOUNDATIONS due to INSULATION? - can we save energy by insulating the foundation without causing a foundation collapse?
- CATHEDRAL CEILING INSULATION - how we insulate and ventilate this common source of heat loss while avoiding moisture, mold, rot
- Ceramic Insulation - version of high temperature treated Perlite Insulation
- COMBUSTION AIR for TIGHT BUILDINGS - assuring safe combustion appliances to prevent carbon monoxide hazards
- DEW POINT TABLE - CONDENSATION POINT GUIDE - technical explanation of indoor condensation problems
- DEW POINT CALCULATION for WALLS - on calculating the point in walls at which moisture will condense
- ENERGY AUDIT - How to Use a Free One - free home energy audits - are they accurate, useful? how to get the most out of an energy audit
- ENERGY SAVINGS in buildings - home page for building energy cost savings designs and systems
- ENERGY SAVINGS PRIORITIES - what is the order in which we should invest in building energy savings measures
- ENERGY SAVINGS MAXIMIZE RETURNS ON - which energy improvements get the most return on investment - how do we calculate that?
- ENERGY SAVINGS RETROFIT CASE STUDY - details of insulating and stopping air leaks in an older home, significant heat cost reduction
- ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE - stopping unwanted heat losses, air leaks, or heat gains on older buildings
- ENERGY SAVINGS RETROFIT OPTIONS - ultralightweight concrete and other energy saving retrofit options
- ENERGY STAR PROGRAM - what is the Energy Star Program?
- ENERGY USE MONITORING, SOLAR - suggestions for monitoring building energy usage, electricity usage, and passive solar house performance
- Environmental Hazard Inspection & Testing - mold, air quality, gases, odors
- EVAPORATIVE COOLING SYSTEMS - using a swamp cooler to reduce energy costs in a building
- ELECTRIC HEAT
- FIBERGLASS INSULATION
- FIBERGLASS HAZARDS - how to recognize potential fiberglass dust hazards, how to test buildings for fiberglass dust levels
- FIBERGLASS INSULATION - how to identify, install, and use fiberglass insulation in buildings and HVAC systems
- Financial Aid for Energy Savings Projects - Energy Star and Home Mortgage assistance
- FLOOR CHOICES OVER CONCRETE SLABS and FLOOR POURED FINISH ON CONCRETE SLABS - finish flooring over thermal mass slabs for passive solar designs
- FRAMING DETAILS for BETTER INSULATION - small details can substantially improve the building envelope insulation R-values
- FREEZE-PROOF A BUILDING - protect from frozen burst pipes, subsequent leaks, mold, water damage in colder buildings
- Green Construction, Green Building Guidelines & Advice
- International Green Construction Code (IGCC) Public Version 2.0, Novembrer 2010 (PDF file), retrieved 12/12/10, original source: http://www.iccsafe.org/CS/IGCC/Pages/IGCCDownloadV2.aspx?r=igccv2
International Green Construction Code (IGCC) - Water Efficiency Provisions Public Version 2.0, Novembrer 2010 (PDF file), retrieved 12/12/10, original source: http://www.iccsafe.org/CS/IGCC/Pages/IGCCDownloadV2.aspx?r=igccv2
LEED GREEN BUILDING CERTIFICATION
LEED Building Designation & IAQ
- GREENHOUSE DESIGN for SOLAR HEATING - details about trombe wall, ventilation, how to obtain solar heat from a greenhouse retrofit or conversion
- HEAT LOSS in buildings - article series on finding and fixing points of building heat loss
- HEAT LOSS DETECTION TOOLS - how we find where a building is losing or gaining heat
- HEAT LOSS R U & K VALUE CALCULATION
- HEAT LOSS (or GAIN) in buildings
- HEAT LOSS (or GAIN) INDICATORS - find where your building is losing (or gaining) heat
- HEAT PUMPS
- HEATING COST FUEL & BTU COST TABLES
- HEATING COST SAVINGS METHODS - reduce home heating bills by tuning, repairing, or updating heating equipment - tuning up the heating system can make a big difference in building heating costs
- Heating Cost Table - current cost per 1000 BTUs to heat a building
- HEATING LOSS DIAGNOSIS-BOILERS
- HEATING LOSS DIAGNOSIS-FURNACES
- HEATING OIL USAGE RATE - what determines how fast heating oil is consumed? How long will a given amount of heating oil in a tank last?
- HEATING SMALL LOADS - design guide for selecting & installing heating systems in energy-efficient homes - old rules of thumb don't work
- Heat Won't Turn Off - Stop Unwanted Heat . how to be sure the heat is completely "off" when it is not wanted or needed
- HOUSE DOCTOR, how-to be - education, training, tools, publications for house doctors: air leaks, heat loss, building energy loss diagnosis and cure
- HOUSEWRAP AIR & VAPOR BARRIERS - Guide to Selecting & Using Sheathing Wrap - House Wrap - Building Exterior Moisture Barriers - house wrap plays a critical role in stopping air leaks and heat losses, even on well-insulated buildings
- HUMIDITY LEVEL TARGET
- ROOF ICE DAM LEAKS
- INDOOR AIR QUALITY IMPROVEMENT GUIDE
- INDOOR AIR QUALITY & HOUSE TIGHTNESS - how to stop air leaks without causing an indoor air quality problem
- INSULATION for GREENHOUSE or SOLARIUM - how to retrofit night time heat loss insulation and concrete floor slab insulation
- INSULATION IDENTIFICATION GUIDE - Guide to all types of insulating materials used in or on buildings. Insulation products Likely to contain asbestos.
- INSULATION INSPECTION & IMPROVEMENT - Guide to building insulation alternatives, R-values, costs, properties;
- correct building insulation, correct ventilation, save on heating & cooling costs
- INSULATION LOCATION - WHERE TO PUT IT - where should we place insulation, vapor barriers, house wrap, and ventilation for comfortable, energy-efficient building design?
- LEED Building Designation & IAQ - current state of indoor air quality standards & IAQ testing standards for green buildings
- LOG HOMES: Energy Efficiency of Log Homes - is a log home as energy-efficient as other construction methods?
- MOISTURE CONTROL in buildings - how to control excess humidity in tight or other buildings, avoid mold, condensation, rot.
- ODORS, Smells, Gases in buildings-Diagnosis & Cure - are odors a problem in energy-efficient homes? track down and cure smells
- Priorities Setting Overall Energy Savings Priorities - what steps to take in what order to save on heating or cooling costs
- RADIANT BARRIERS - do they work, where to put them, how much energy do they save for cooling vs. heating needs?
- RADIANT HEAT - strategy for using radiant heat in buildings
- RADIANT HEAT FLOOR MISTAKES - avoid these horrible mistakes that led to abandonment of a radiant heated floor slab
- RADIANT SLAB TUBING & FLUID CHOICES - types of plastic tubing for radiant heated slabs; types of heat conducting fluids
- REMOTE ELECTRIC POWER, PHOTOVOLTAIC how to obtain electrical power at a remote site using photovoltaic solar panels or wind generators.
- ROOFING INSPECTION & REPAIR - articles related to solar & energy conservation (also see Ventilation in buildings)
- SEER RATINGS & OTHER DEFINITIONS - measuring the energy efficiency of air conditioning equipment
- SHEATHING, FOIL FACED - VENTS - do we need to vent walls insulated with foil faced sheathing?
- SIDING WOOD, FAILURES OVER FOAM BOARD - proper installation, maintenance, and moisture control avoid damage
- SLAB INSULATION, PASSIVE SOLAR - how much insulation, where to put it, and where to put the vapor barrier below a heated floor slab
The green power solar electrical panel array shown above is distributed by Desmex Solar and is installed in San Miguel de Allende, Mexico. This solar energy system provides all of the electrical energy required by a small restaurant, including powering lighting and nine refrigerators and coolers in the building.
- SOLAR ENERGY SYSTEMS - passive solar, thermal mass, window glazing, building insulation and ventilation, sunspaces cut energy costs
- BLOCKBED RADIANT FLOORS - SOLAR DESIGN - how we design a concrete block floor for thermal mass &radiant heat distribution, flow rates, air movement, block sizes, etc.
- PASSIVE SOLAR DESIGN HANDBOOK - 3 volumes of detailed solar design specs from the USAF (PDF files)
- PASSIVE SOLAR DESIGN KEY ELEMENTS - what are the key elements in passive solar design? - US DOE (supplemented with additional photos, commentary, text)
- PASSIVE SOLAR DESIGN METHOD - combination solar systems involving water well, direct gain, and Trombe wall in one building
- PASSIVE SOLAR HEAT PERFORMANCE - how to more accurately calculate the passive solar contribution to energy savings
- PASSIVE SOLAR HOME, LOW COST - case study describes a low-budget but highly effective passive solar home
- SLAB INSULATION, PASSIVE SOLAR - what insulation thickness is needed under a passive-solar heated slab floor?
- SOLAR COLLECTOR AIR or GAS COLLECTION - does air collecting in solar panels mean corrosion? how to purge solar collector air.
- SOLAR COLLECTOR FILMS - do light-transmitting, heat reflecting films offer efficiency gains for solar collectors?
- SOLAR HEATING SYSTEMS
- Solar Design Books and Guides
- PASSIVE SOLAR DESIGN KEY ELEMENTS - what are the key elements in passive solar design? - US DOE (supplemented with additional photos, commentary, text) - Online text
- Passive Solar Design Handbook Volume I, the Passive Solar Handbook Introduction to Passive Solar Concepts, in a version used by the U.S. Air force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v1.pdf
- Passive Solar Design Handbook Volume II, the Passive Solar Handbook Comprehensive Planning Guide, in a version used by the U.S. Air force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v2.pdf [This is a large PDF file that can take a while to load]
- Passive Solar Handbook Volume III, the Passive Solar Handbook Programming Guide, in a version used by the U.S. Air force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v3.pdf
- The Passive Solar Design and Construction Handbook, Steven Winter Associates (Author), Michael J. Crosbie (Editor), Wiley & Sons, ISBN 978-047118382 or 0471183083 is available at Amazon.com and via the The Passive Solar Design and Construction Handbook, Steven Winter Associates (Author), Michael J. Crosbie (Editor), Wiley & Sons, ISBN 978-047118382 or 0471183083 is available at Amazon.com and via the InspectAPedia Bookstore
- "Passive Solar Home Design", U.S. Department of Energy, describes using a home's windows, walls, and floors to collect and store solar energy for winter heating and also rejecting solar heat in warm weather.
- Solar Swimming Pool Heating
- SOLAR WATER HEATERS - sources & types of solar hot water heating systems
- SOUND CONTROL in buildings - insulating for sound control can also stop convective loops that steal heat from interior walls
- STRESS SKIN INSULATED PANELS - energy savings and construction properties of foam core panels
- SUPER HI-R INSULATION - very high R-value products for super insulated buildings and other applications
- SUNGAIN, FILMS, LOW-E GLASS - review of window and glazing glass coating, number of layers of glazing, low-e, energy efficiency
- SUPER HI-R INSULATION - very high R-value products for super insulated buildings and other applications
- THERMAL MASS in BUILDINGS - how we conserve warmth, coolness, for even building temperatures & lower heating/cooling costs
- THERMAL TRACKING - shows where heat losses and air leaks are occurring in buildings
- THERMOSTATS - how to set and use thermostats to save energy in buildings
- VAPOR BARRIERS & AIR SEALING at BAND JOISTS
- VAPOR BARRIERS & CONDENSATION in buildings
- VAPOR BARRIERS & HOUSEWRAP
- VENTILATION, BALANCED HEAT COST SAVINGS - how to calculate heating cost savings from correcting the building air change rate and using balanced ventilation systems
- VENTILATION in BUILDINGS - proper building ventilation design, stopping air bypass leaks, avoiding condensation in tight homes
- WET BASEMENT PREVENTION
- WIND TURBINES & LIGHTNING - how to protect controls and circuits from lightning damage
- WINDOWS & DOORS - home page for articles on identifying, installing, troubleshooting, & energy efficiency of all types of building windows & doors
- WINTERIZE A BUILDING - protect a building & its mechanical systems from freeze-damage at low temperatures & deep heat setbacks
- WOOD Burning Heaters Fireplaces Stoves - supplemental heat for solar and other alternative or renewable energy design homes
Qualified service providers specializing in topics discussed at this website may (at our discretion) be listed at this website at no fee.
U.S. EPA Description of Types of Renewable Energy Sources
Onsite Renewable Technologies - US EPA List:
In the United States, electricity is generated primarily from the combustion of a limited supply of fossil fuels, or with large hydroelectric dams, or with nuclear power plants. Each of these traditional approaches presents unique environmental concerns. Renewable energy dramatically lowers pollution emissions, reduces environmental health risks, and slows the depletion of finite natural resources.
Renewable energy is derived from sun, wind, water, or the Earth's core. It also can be derived from biomass—or plant matter—which is grown, harvested, and transferred into energy by one of a number of processes. Renewable technologies are designed to capture and store this energy. They include:
- Photovoltaic solar panels convert sunlight directly into electricity. - see SOLAR ENERGY SYSTEMS
- Wind turbines capture wind to turn rotors, which turns a generator and creates electricity. - see WIND TURBINES & LIGHTNING
- Transpired solar collectors use sunlight to preheat air for heating purposes. - see SOLAR ENERGY SYSTEMS
- Solar hot water heaters use the sun to heat water for domestic applications. - see SOLAR ENERGY SYSTEMS
- Small-scale hydroelectric power plants flow water over turbines, which turn a generator and create electricity.
- Fuel cells combine hydrogen and oxygen to produce electricity and heat.
- Ground-source heat pumps transfer heat to the ground in summer and extract heat from the ground in winter.
- Green power is electricity generated from renewable sources such as wind, geothermal, biomass, and landfill gas.
Because use of renewable energy sources can involve purchase of equipment (solar collectors, wind generators) early in the development life of those systems, and because analysis of the economic costs can be complex, readers should review the topics listed above and at the "More Reading" links at the bottom of this article , and in particular, also see energy savings articles listed at
Home Mortgage Assistance for Buying Already-Energy-Efficient buildings
The Energy StarProgram defines a variety of home mortgage options that can give home owners or home buyers assistance for energy-efficient buildings. Readers should notice that these programs are aimed at purchasers of homes that are surveyed and rated as energy efficient before the purchase - not to finance energy improvement retrofits. However, there may be federal or local programs that do provide financial assistance for building weatherization and insulation retrofits.
Check with your local building department, state, town, or county financial assistance offices, and office for the elderly or aging in your community. Also check with building renovation programs intended to help people who own their home but are of very limited financial means, such as the Christmas in April program.
According to EnergyStar, (quoting from the Energy Star source)
An Energy Efficient Mortgage (EEM) is a mortgage that credits a home’s energy efficiency in the mortgage itself. EEMs give borrowers the opportunity to finance cost-effective, energy-saving measures as part of a single mortgage and stretch debt-to-income qualifying ratios on loans thereby allowing borrowers to qualify for a larger loan amount and a better, more energy-efficient home.
To get an EEM a borrower typically has to have a home energy rater conduct a home energy rating before financing is approved. This rating verifies for the lender that the home is energy-efficient.
EEMs are typically used to purchase a new home that is already energy efficient such as an ENERGY STAR qualified home. The term EEM is commonly used to refer to all types of energy mortgages including Energy Improvement Mortgages (EIMs), which are used to purchase existing homes that will have energy efficiency improvements made to them. EIMs allow borrowers to include the cost of energy-efficiency improvements to an existing home in the mortgage without increasing the down payment. EIMs allow the borrower to use the money saved in utility bills to finance energy improvements. Both EEMs and EIMs typically require a home energy rating to provide the lender with the estimated monthly energy savings and the value of the energy efficiency measures — known as the Energy Savings Value.
EEMs (and EIMs) are sponsored by federally insured mortgage programs (FHA and VA) and the conventional secondary mortgage market (Fannie Mae and Freddie Mac). Lenders can offer conventional EEMs, FHA EEMs, or VA EEMs.
Conventional Energy Efficient Mortgages described by Energy Star
Conventional EEMs can be offered by lenders who sell their loans to Fannie Mae and Freddie Mac. Conventional EEMs increase the purchasing power of buying an energy efficient home by allowing the lender to increase the borrower’s income by a dollar amount equal to the estimated energy savings. The Fannie Mae loan also adjusts the value of the home to reflect the value of the energy efficiency measures. For more information about Fannie Mae's EEM you can call 1-800-7FANNIE (732-6643).
FHA Energy Efficient Mortgages described by Energy Star
FHA EEMs allow lenders to add 100 percent of the additional cost of cost-effective energy efficiency improvements to an already approved mortgage loan (as long as the additional costs do not exceed $4000 or 5 percent of the value of the home, up to a maximum of $8000, whichever is greater). No additional down payment is required, and the FHA loan limits won’t interfere with the process of obtaining the EEM. FHA EEMs are available for site-built as well as for manufactured homes. Applications for an FHA EEM may be submitted to the local HUD Field Office through an FHA-approved lending institution.
VA Energy Efficient Mortgages described by Energy Star
The Veteran’s Administration (VA) EEM is available to qualified military personnel, reservists and veterans for energy improvements when purchasing an existing home. The VA EEM caps energy improvements at $3,000–$6,000. Borrowers should ask their lender about a VA EEM at the beginning of the lending process.
To learn more about EEMs contact Fannie Mae, Freddie Mac, the FHA or the VA. Additional information about writing energy-efficient mortgages can be found on their Web sites.
ENERGY STAR Mortgages described by Energy Star at their Website
An ENERGY STAR mortgage pilot program is underway to demonstrate that financing can be a useful tool for enhancing the success of investing in energy-efficient homes by lowering borrowing costs, as well as demonstrating the importance of utilizing a network of qualified energy auditors and contractors to ensure that cost-effective energy efficiency improvements are realized.
By incorporating the costs of energy efficiency improvements into the loan itself, an ENERGY STAR mortgage allows borrowers to pay for those investments over the life of their loan and deduct the interest from their federal and state income taxes. One of the key benefits of an ENERGY STAR mortgage is that a borrower can finance and make energy-saving improvements to their homes without paying more for financing than they would for a typical mortgage. Participating lenders also offer borrowers an additional financial benefit above and beyond the value of the home energy savings, such as discounted mortgage rates, reduced loan fees, or assistance with closing costs.
Radiant floor heating vs cooling: what about a balance between summer cooling and winter heating
In south central Tennessee near Alabama we are building a small 1700 ft2 home. Three sides and the roof are completely enclosed in hillside soil with a 2 feet of soil over roof. We are installing radiant floor heating with an air handler back-up. Both will be hot water heated via wood burning boiler.
We have an annual temperature range from the low teens to the high nineties (degrees F). Our intention is to employ edge insulation but NOT floor insulation on the concrete slab floor. Our thinking is this will allow for radiant cooling in the summer and we will “pay” a manageable cost in performance during the winter.
We are pouring in two weeks and would greatly appreciate a response to this question: ARE WE ABOUT TO MAKE A BIG MISTAKE? Thanks. Sincerely Jim and Larry - Homeowners doing the work.
Reply: Match the building insulation plan and heating and cooling design to the climate
Steven Bliss & Daniel Friedman
Jim and Larry, your project is far enough south that the benefit from cooling, using the earth as a heat sink or a source of cooling in hot weather may outweigh the cost of heating in cool weather.
I have been very critical of uninsulated slabs in cold climates where the heating load is significant (see RADIANT HEAT FLOOR MISTAKES) . But I did not intend to suggest that in a climate where cooling costs are high that the data works out to the same conclusion nor that all buildings should have the same design regardless of climate.
Radiant Heating vs Radiant Cooling Floor Design Contrasts
Just to get a technical point out of the way, while we may speak of "radiant heating" it does not quite work the same way to speak of "radiant cooling". That is, a warm floor surface may heat surrounding objects by radiant heat - a method that many homeowners say is quite comfortable. But during hot weather a cooler floor doesn't "radiate" coolness - it won't blow cool air as does a conventional air conditioner or heat pump (though it might - see our article recommendations below).
Rather, heat radiating from hot or warm objects in the room will find some absorption by the cooler floor surface. So the room is radiating heat back to the floor, though I suspect with less efficiency in cooling mode than in heating mode. Why?
A large warm floor surface has an easy time radiating heat upwards into a cooler room area and onto objects in that room, as warmer air at the floor surface and around objects rises. Heat and warmth and warm air tend to move upwards in warm buildings - away from, rather than towards the floor.
I'm not sure it's as easy to move heat "down" in a passive design. In sum, while I think of radiant heating as an understandable approach to warming a building, I don't think of "radiant cooling" sending "coolness upwards" into the occupied space. Coolness won't move up, but heat may move down, a bit.
Compare Construction Costs vs. Energy Costs to Heat & Cool over Building Life
You'll want to estimate cooling and heating costs including anticipated energy cost rises in the future as well as energy cost comparisons between electric and fossil fuels, depending on how you are going to heat vs cool the home.
One could certainly compare two designs:
A: Summer cooling making use of the heat-absorbing properties of an uninsulated floor slab in good thermal contact with the cooler earth below, paying higher heating costs during the heating season due to heat losses through the floor.
B. Summer cooling making use of the heat-absorbing properties of an insulated floor slab and thermal mass below the slab, still insulating the slab from the earth below, making use of the same slab as a heat sink and reservoir during the heating season. This approach may save on energy costs but will have a higher build cost.
Thermal Mass and Building Energy Costs: reduced cooling loads in some climates
High-mass houses have been studied extensively by the log home industry and concrete industry through sophisticated computer modeling and field testing. They were intent on proving that the “mass effect” of high-mass buildings helped save energy independent of the R-value of the components. Their goal was to prove that log homes or, in the case of the concrete industry, concrete homes were inherently energy-efficient. Their efforts were somewhat successful in that ASHRAE, the organization that sets standards for the thermal performance of buildings now recognizes that thermal mass plays a modest role in a building’s performance (see ASHRAE Standard 90.1).
The benefit is mainly to reduce cooling loads in climates with hot days and cold nights. It does this by damping the temperature swing inside the space. Think adobe buildings in the high, arid Southwest where it may be 90°F during the day and 40°F at night. The high mass walls will keep the indoor temperature closer to the average of these two temperatures and thus more comfortable – reducing or eliminating the need for mechanical cooling, especially in arid areas where dehumidification is not needed.
When the outdoor temperatures are above the human comfort level, both day and night, such as in Florida in summer, thermal mass has much less value. It will cause a lag in the indoor peak temperature, relative to outdoors, but that may and may not be beneficial.
Thermal mass has less benefit for heating, and probably no benefit in cold climates when the winter temperature stays below the comfort level all day and night -- as in the northern U.S. in winter. One effect of a high-mass home, is that it is difficult to quickly heat up the house – which is why setback thermostats are not recommended in homes with radiant slabs. It’s also why direct-gain passive solar homes perform poorly in cold, cloudy weather. If the thermal mass is allowed to cool off during these periods, it takes a long time to heat up the building and the mass provides radiant cooling – when you need it the least!
Balanced Temperature Swings & Thermal Mass Benefits
One can observe that at locations where average day and night temperatures swing just about the same around a comfortable indoor temperature range, thermal mass alone can provide significant comfort in buildings and much less outside energy may be needed to heat or cool the home.
At PASSIVE SOLAR HEAT PERFORMANCE
at PASSIVE SOLAR HOME, LOW COST we illustrate homes located at an elevation of about 6300 ft. in central Mexico. Although it's not quite in perfect balance, a home in San Miguel de Allende (described at x) has been considered by its occupants (DF & family) to be comfortable enough as to not require central heating nor air conditioning. The structure, built of plastered adobe and concrete, has a high thermal mass. Passive solar gain warms the structure during the day, providing heat that is returned in cooler evenings; during warmer parts of the day the still-cool mass of the structure helps keep indoor temperatures comfortable.
At Technical Reviewers & REFERENCES we include references to other sources on this topic. Reference  seems to contain an error, in the section: “Nearly all areas with significant cooling loads can benefit from thermal mass in exterior walls. The sunny Southwest, particularly high-elevation areas of Arizona, New Mexico and Colorado, benefit the most from the mass effect for heating.” I think they meant to say “cooling.” Reference , a blog posting of the same information, gets this right.
Mass-Enhanced "R" Value
In a thoughtful article about mass-enhanded R-value, BuildCentral reports that while thermal mass can outperform low-mass building walls (or in your case floors) of the same R-value, deciding if a particular building will benefit from this design requires some careful thought. Quoting:
The mass effect is real. High-mass walls really can significantly outperform low-mass walls of comparable steady-state R-value--i.e., they can achieve a higher "mass-enhanced R-value." BUT (and this is an important "but"), this mass-enhanced R-value is only significant when the outdoor temperatures cycle above and below indoor temperatures within a 24-hour period. Thus, high-mass walls are most beneficial in moderate climates that have high diurnal (daily) temperature swings around the desired indoor setpoint. 
Thermal Mass & Passive Solar Energy Systems for Heating, Cooling, or Both
We discuss thermal mass in building floors in passive solar designs
at SLAB INSULATION, PASSIVE SOLAR
at BLOCKBED RADIANT FLOORS - SOLAR DESIGN.
Also see PASSIVE SOLAR FLOOR TILES, PHASE CHANGE
And see See SLATE THERMAL MASS for SOLAR HEAT STORAGE.
And at FLOOR CHOICES OVER CONCRETE SLABS we illustrate a floor slab (with incomplete under-slab insulation) that provides thermal mass helping to stabilize temperatures in a cabin in torthern Minnesota.
We no longer recommend solar rock bins as thermal mass or for thermal storage. These were largely discredited by Solar Age and others as ineffective, expensive, and prone to all manner of problems with mold, poor airflow, etc.
As for modeling thermal mass effects and earth-sheltering, it’s usually done on mainframes using DOE BLAST, so it’s not for the faint hearted or anyone else who doesn’t have a PhD in physics.
Thermal Mass & Active Solar Energy Systems for both Heating & Cooling
Take a look at
Active Solar Rock-bed Heat Storage Design Details: Active Solar Energy Systems, and also Active Solar Blockbed Floor Design for examples of using thermal mass to control both heating and cooling cost, and in the case of the second article, including active cooling by routing building air through passages in the thermal-mass of a cool floor.
Both of those approaches presume that the thermal mass is nevertheless insulated from the earth, so that it can benefit both heating and cooling seasons.
In sum, my OPINION is that you are considering a design that has appeal for simplicity and lower installation cost. But before deciding you might want to look at both active and passive solar designs that make use of thermal mass, often an insulated thermal mass, to reduce both summer cooling and winter heating costs.
Steven Bliss adds:
I did a follow-up where-are-they-now study once at Solar Age, looking at well-known solar and alternative houses including a couple of earth-sheltered houses built by Malcolm Wells, one of the widely published proponents of living underground. To make a long story short, I contacted the owners who had recently removed all the earth from their roof due to mysterious pinhole leaks in the rubber roof, which maybe wasn’t designed to have tons on earth overhead.
Living underground is not for everyone – anymore than everyone would want to live in someone’s basemet
Continue reading at AFUE DEFINITION, RATINGS or select a topic from the More Reading links shown below.
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ENERGY SAVINGS in buildings at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.
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- Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
- Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference Book, a reference & inspection report product for building owners & inspectors.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones.
Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
- The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones
- Wikipedia provided background information about some topics discussed at this website provided this citation is also found in the same article along with a " retrieved on" date. NOTE: because Wikipedia entries are fluid and can be amended in real time, we cite the retrieval date of Wikipedia citations and we do not assert that the information found there is necessarily authoritative.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
- The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.